Nearing its 40th anniversary, the San Francisco-based Alexander String Quartet is widely admired for its interpretations of Mozart and Beethoven, but it is no stranger to new music. The group will play the Mozart String Quartet in C Major, K. 465 “Dissonant,” and the Brahms String Quartet in C minor, Op. 51, No. 1. Debussy’s String Quartet in G minor, Op. 10 will follow the intermission. The only string quartet Debussy wrote, it has become one of the most admired in the repertoire because of its stunning sensual beauty and the variety of textures it requires of the instruments.